The present invention relates to the field of communications and more particularly to methods of providing signal-to-interference ratios and related systems and terminals.
In a cellular communications system, it may be desirable to dynamically control a power of downlink transmissions from a base station to a mobile terminal. According to the IS-95 B (CDMA) standard, for example, a mobile terminal may transmit a single bit to the base station indicating whether the previous frame was in error or not, and the base station may adjust the downlink transmission power accordingly. An indication of a transmission error, however, may only provide a relatively crude indication of signal quality.
According to the IS-2000 and UMTS standards, the mobile terminal may instruct the base station to raise or lower the downlink transmission power by 1 dB depending on a quality of downlink transmissions received from the base station. The mobile terminal may, thus, perform additional processing steps to make the power control determinations.
According to the GSM and IS-136 standards, a provision for slow downlink power control may be based on signal quality measurements received by the base station from the mobile terminal at approximately 0.5 to 1 second intervals. Power control based on signal quality measurements received over 0.5 to 1.0 second intervals, however, may be unable to accommodate faster radio channel variations.